Charlie, Gambit, Rogue, and Rose appear in the background in the 'Showdown in the Park' stage.

Blanka (of "Street Fighter" fame) can be seen within the background in the 'Death Valley' stage.

Dan's ending is an obvious parody of the ending of the SNK game, "Art of Fighting".

Sunburned (or Evil) Sakura has two separate endings (Japanese version): Kei chases Gouki and Sunburned Sakura after they teleport away
1) Across the entire screen from right to left.
2) Across half the screen before she trips, falls, and falls asleep.

There are several cameos of Rockman in this game:
1) In the mall stage, there's a cameo of a Rockman cut-out (perhaps someone in a Rockman suit). And in relation to Capcom celebrating Rockman's "10th Anniversary" in 1997, they put a banner saying '10th Anniversary: Rockman'.
2) In one of Norimaro's super combos, he does a cosplay of Rockman.

There is one rumored reason why Iron Man was not in this game. It is because Acclaim made an Iron Man game called "Iron Man and X-O Manowar in Heavy Metal" which was released for several consoles.

Firstsmile released a limited-edition soundtrack album for this game (Marvel Super Heroes Vs. Street Fighter Original Soundtrack & Arrange - FSCA-10017) on September 19, 1997.

Green Board revisions :

REVISION 1: Build date: 970625

REVISION 2: Build date: 970702

REVISION 3: Build date: 970707

ADDITIONAL NOTES:
The Japanese version features an extra playable character (his character slot on the character select screen is replaced by the MSH vs. SF logo on all non-Japanese versions), Norimaro, a silly otaku (Japanese geek specializing in anime and manga) who is a huge Chun-Li fanboy as evidence by his reaction in seeing her before the match begins. While his true intentions of entering the competition is unknown, we can assume that it was to take pictures of Chun-Li and the many superheroes. He is voiced by the comedian Kinashi Noritake and created by Capcom as being a joke character like Dan (modeled after a Japanese comedian Noritake Kinashi). He was originally going to appear in non-Japanese versions of the game, but due to cultural differences and a reference to stealing Chun-Li's panties in his ending, he was cut out. However, his programming still exists in the ROM and he even has English dialogs in the game. He even has an ending with pictures, but his ending dialogs was cut out.

Play as Evil Sakura : At the character selection screen, highlight Hulk, hold Right for 5 sec. and press LP+HP or LK+HK.

Play as Evil Zanglief : At the character selection screen, highlight Blackheart, hold Left for 5 sec. and press LP+HP or LK+HK.

Play as Armored Spiderman : At the character selection screen, highlight Ryu, move down and hold Down for 5 sec. and press LP+HP or LK+HK.

Play as Mephisto : At the character selection screen, highlight Omega Red, hold Down for 5 sec. and press LP+HP or LK+HK.

Play as U.S. Agent : At the character selection screen, highlight Bison, hold Up for 5 sec. and press LP+HP or LK+HK.

Play as Shadow Charlie : At the character selection screen, highlight Dhalsim, hold Up for 5 sec. and press LP+HP or LK+HK.

Play as Gambit : Go to Dhalsim, hold Start, then move Left(x2), Down(x4), Right(x2), Up(x2), Right and press and hold LP+MK+HP together.

Play as Norimaro (Japanese version only) : Norimaro will show on the character select screen (bottom middle square) if the machine is set to Freeplay or 1 coin X credit. A setting of 2 coins or above and you will only see the Marvel Super Heroes Vs. Street Fighter logo in his square.

Beat 'em While They're Down : After defeating your opponents, press and hold Start. Normally your character wont be able to move after the round is over but by holding Start you will not only be able to move freely (until the next round starts) but you will be able to hit your opponent and even do a Super on them!

Change Battle Order : When the screen shows which teams will be battling, press Punch or Kick three times to change the order of battle.

Double Team Spidermen : Start a new game and choose any character for your first choice followed by Spiderman as the second character. Deliberately lose, then continue and choose Silver Spiderman as your first character. The other Spiderman should be selected as your second character.

Fight Secret Characters (Japanese Version) : To fight a secret character in the Japanese version you must do a certain amount of team super finishes :
Character #
Evil Sakura 5
Evil Zangief 6
Shadow Charlie 7

Hyper Mode : At the vs. screen, hold LK+MP+HK.

Dan's Explosion : Pick Dan as your fighter and anyone else. At the Vs. screen hold LP until the word fight disappears. When the match begins Dan will fall into a small explosion.